What is Magnetic Resonance Imaging?
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body.
Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily aligns the water molecules in your body. Radio waves cause these aligned particles to produce very faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.
The MRI machine can also be used to produce 3-D images that may be viewed from many different angles.
Why it’s done
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images that help diagnose a variety of problems.
MRI of the brain and spinal cord
MRI is the most frequently used imaging test of the brain and spinal cord. It’s often performed to help diagnose:
- Disorders of the eye and inner ear
- Multiple sclerosis
- Spinal cord injuries
Functional MRI of the brain (fMRI) can be used to identify important language and movement control areas in the brain in people who are being considered for brain surgery.
MRI of the heart and blood vessels
An MRI that focuses on the heart or blood vessels can assess:
- The size and function of the heart’s chambers
- Thickness and movement of the walls of the heart
- The extent of damage caused by heart attack or heart disease
- Structural problems in the aorta, such as aneurysms or dissections
- The buildup of plaques and blockages in the blood vessels
MRI of other internal organs
An MRI may be used to check for tumors or other abnormalities of many organs in the body, including the:
MRI of bones and joints
MRI may be used to help evaluate:
- Joint disorders, such as arthritis
- Joint abnormalities caused by traumatic or repetitive injuries
- Disk abnormalities in the spine
- Bone infections
- Tumors of the bones and soft tissues
MRI of the breasts
MRI may be used in addition to mammography to detect breast cancer, particularly in women who have dense breast tissue or who may be at high risk of the disease.